Sustainable soil remediation by refrigerated condensation at sites with “high‐concentration” recalcitrant compounds and NAPL: Two case studies

Remediation of recalcitrant compounds at sites with high concentrations of volatile organic compounds (VOCs) or nonaqueous‐phase liquids (NAPLs) can present significant technical and financial (long‐term) risk for stakeholders. Until recently, however, sustainability has not been included as a significant factor to be considered in the feasibility and risk evaluation for remediation technologies. The authors present a framework for which sustainability can be incorporated into the remediation selection criteria focusing specifically on off‐gas treatment selection for soil vapor extraction (SVE) remediation technology. SVE is generally considered an old and standard approach to in situ remediation of soils at a contaminated site. The focus on off‐gas treatment technology selection in this article allows for more in‐depth analysis of the feasibility evaluation process and how sustainable practices might influence the process. SVE is more commonly employed for recovery of VOCs from soils than other technologies and generally employs granular activated carbon (GAC), catalytic, or thermal oxidation, or an emerging alternative technology known as cryogenic‐compression and condensation combined with regenerative adsorption (C3–Technology). Of particular challenge to the off‐gas treatment selection process is the potential variety of chemical constituents and concentrations changing over time. Guidance is available regarding selection of off‐gas treatment technology (Air Force Center for Environmental Excellence, 1996; U.S. Environmental Protection Agency, 2006). However, there are common shortcomings of off‐gas treatment technology guidance and applications; practitioners have rarely considered sustainability and environmental impact of off‐gas treatment technology selection. This evaluation includes consideration of environmental sustainability in the selection of off‐gas treatment technologies and a region‐specific (Los Angeles, California) cost per pound and time of remediation comparisons between GAC, thermal oxidation, and C3–Technology. © 2008 Wiley Periodicals, Inc.     

Treatment technology for remediation of wood preserving sites: Overview

This is the first in a series of five articles describing the applicability, performance, and cost of technologies for the remediation of contaminated soil and water at wood preserving sites. Site‐specific treatability studies conducted under the supervision of the United States Environmental Protection Agency (US EPA), National Risk Management Research Laboratory (NRMRL), from 1995 through 1997 constitute much of the basis for the evaluations presented, although data from other treatability studies, literature sources, and actual site remediations have also been included to provide a more comprehensive evaluation of remediation technologies. This article provides an overview of the wood preserving sites studied, including contaminant levels, and a summary of the performance of the technologies evaluated. The subsequent articles discuss the performance of each technology in more detail. Three articles discuss technologies for the treatment of soils, including solidification/stabilization, biological treatment, solvent extraction and soil washing. One article discusses technologies for the treatment of liquids, water and nonaqueous phase liquids (NAPLS), including biological treatment, carbon adsorption, photolytic oxidation, and hydraulic containment. The reader should be aware that other technologies including, but not limited to, incineration, thermal desorption, and base catalyzed dehalogenation, also have application for treating contaminants on wood preserving sites. They are not discussed in these five articles since the focus was to evaluate lesser known and hopefully lower cost approaches. However, the reader should include consideration of these other technologies as part of any evaluation or screening of technologies applicable to remediation of wood preserving sites.     

The challenge of remediation technology development

A huge commercial environmental industry, currently estimated at some $130 billion in size in the United States alone, has sprung up to manage and remediate environmental problems. Hundreds of innovative remediation technologies are being developed under EPA's SITE program, which has provided R&D funding for more than 100 new treatment technologies. Despite the obvious demand, numerous regulatory, marketing, technical, and financial barriers have impeded progress in the field of remediation technology development. Developers of remediation technologies are faced with a significant challenge to overcome these barriers and successfully bring a technology to market. This article examines the barriers to technology development and offers strategic planning alternatives for long-term economic success and commercial viability of remediation technologies.     

SITE Program Success: Cost Savings to Government and Increased Revenue for Technology Vendors

The Superfund Innovative Technology Evaluation (SITE) program is a program mandated by Congress through the 1986 Superfund Amendments and Reauthorization Act (SARA). The original Superfund allowed no provisions for research and development of needed remediation technologies. Problems arose when the demand for involved, complex treatment could not be met by the traditional contain, haul, and dispose process that hazardous waste handlers had become familiar with. In response to the increasing complexity of hazardous waste site remediation, SARA called for an “Alternative or Innovative Treatment Technology Research and Demonstration Program.” As a result, EPA's Office of Solid Waste and Emergency Response and the Office of Research and Development established the SITE program. This article is a historical analysis of the unique cost savings of the SITE program.     

PFAS Experts Symposium: Statements on regulatory policy,chemistry and analytics,toxicology, transport/fate,and remediation for per‐ and polyfluoroalkyl substances (PFAS) contamination issues

Sixty leading members of the scientific, engineering, regulatory, and legal communities assembled for the PFAS Experts Symposium in Arlington, Virginia on May 20 and 21, 2019 to discuss issues related to per‐ and polyfluoroalkyl substances (PFAS) based on the quickly evolving developments of PFAS regulations, chemistry and analytics, transport and fate concepts, toxicology, and remediation technologies.  The Symposium created a venue for experts with various specialized skills to provide opinions and trade perspectives on existing and new approaches to PFAS assessment and remediation in light of lessons learned managing other contaminants encountered over the past four decades. The following summarizes several consensus points developed as an outcome of the Symposium:

• Regulatory and policy issues: The response by many states and the US Environmental Protection Agency (USEPA) to media exposure and public pressure related to PFAS contamination is to relatively quickly initiate programs to regulate PFAS sites. This includes the USEPA establishing relatively low lifetime health advisory levels for PFAS in drinking water and even more stringent guidance and standards in several states. In addition, if PFAS are designated as hazardous substances at the federal level, as proposed by several Congressional bills, there could be wide‐reaching effects including listing of new Superfund sites solely for PFAS, application of stringent state standards, additional characterization and remediation at existing sites, reopening of closed sites, and cost renegotiation among PRPs.
• Chemistry and analytics: PFAS analysis is confounded by the lack of regulatory‐approved methods for most PFAS in water and all PFAS in solid media and air, interference with current water‐based analytical methods if samples contain high levels of suspended solids, and sample collection and analytical interference due to the presence of PFAS in common consumer products, sampling equipment, and laboratory materials.
• Toxicology and risk: Uncertainties remain related to human health and ecological effects for most PFAS; however, regulatory standards and guidance are being established incorporating safety factors that result in part per trillion (ppt) cleanup objectives. Given the thousands of PFAS that may be present in the environment, a more appropriate paradigm may be to develop toxicity criteria for groups of PFAS rather than individual PFAS.
• Transport and fate: The recalcitrance of many perfluoroalkyl compounds and the capability of some fluorotelomers to transform into perfluoroalkyl compounds complicate conceptual site models at many PFAS sites, particularly those involving complex mixtures, such as firefighting foams. Research is warranted to better understand the physicochemical properties and corresponding transport and fate of most PFAS, of branched and linear isomers of the same compounds, and of the interactions of PFAS with other co‐contaminants such as nonaqueous phase liquids. Many PFAS exhibit complex transport mechanisms, particularly at the air/water interface, and it is uncertain whether traditional transport principles apply to the ppt levels important to PFAS projects. Existing analytical methods are sufficient when combined with the many advances in site characterization techniques to move rapidly forward at selected sites to develop and test process‐based conceptual site models.
• Existing remediation technologies and research: Current technologies largely focus on separation (sorption, ion exchange, or sequestration). Due to diversity in PFAS properties, effective treatment will likely require treatment trains. Monitored natural attenuation will not likely involve destructive reactions, but be driven by processes such as matrix diffusion, sorption, dispersion, and dilution.

The consensus message from the Symposium participants is that PFAS present far more complex challenges to the environmental community than prior contaminants. This is because, in contrast to chlorinated solvents, PFAS are severely complicated by their mobility, persistence, toxicological uncertainties, and technical obstacles to remediation—all under the backdrop of stringent regulatory and policy developments that vary by state and will be further driven by USEPA. Concern was expressed about the time, expense, and complexity required to remediate PFAS sites and whether the challenges of PFAS warrant alternative approaches to site cleanups, including the notion that adaptive management and technical impracticability waivers may be warranted at sites with expansive PFAS plumes. A paradigm shift towards receptor protection rather than broad scale groundwater/aquifer remediation may be appropriate.     

Sustainable Remediation Considerations for Treatment of 1,4‐Dioxane in Groundwater

1,4‐Dioxane remediation is challenging due to its physiochemical properties and low target treatment levels. As such, applications of traditional remediation technologies have proven ineffective. There are a number of promising remediation technologies that could potentially be scaled for successful application to groundwater restoration. Sustainable remediation is an important consideration in the evaluation of remediation technologies. It is critically important to consider sustainability when new technologies are being applied or new contaminants are being treated with traditional technologies. There are a number of social, economic, and environmental drivers that should be considered when implementing 1,4‐dioxane treatment technologies. This includes evaluating sustainability externalities by considering the cradle‐to‐grave impacts of the chemicals, energy, processes, transportation, and materials used in groundwater treatment. It is not possible to rate technologies as more or less sustainable because each application is context specific. However, by including sustainability thinking into technology evaluations and implementation plans, decisions makers can be more informed and the results of remediation are likely to be more effective and beneficial. There are a number sustainable remediation frameworks, guidance documents, footprint assessment tools, life cycle assessment tools, and best management practices that can be utilized for these purposes. This paper includes an overview describing the importance of sustainability in technology selection, identifies sustainability impacts related to technologies that can be used to treat 1,4‐dioxane, provides an approximating approach to assess sustainability impacts, and summarizes potential sustainability impacts related to promising treatment technologies. ©2016 Wiley Periodicals, Inc.     

Using an integrated approach for quantifying VOC source areas for site remediation

Locating and quantifying free-phase volatile organic compounds (VOCs) in the subsurface represent one of the more difficult challenges facing hazardous waste site remediation programs. Successful remediation programs require reliable data on the size and extent of potential VOC contamination sources. Improving subsurface quantification of VOCs requires a large number of reliable low-cost samples. Satisfying this objective relies on improved sampling techniques, field analysis of samples, and a modified quality assurance program. This paper describes an integrated approach using conventional split-spoon samplers, microcore sampling, hexane extractions, and a field gas chromatograph with an autosampler as part of a technical demonstration for innovative remediation technologies. Using this approach, it was possible to delineate a subsurface source of free-phase VOCs at a cost of $15 per sample. The distribution of dense nonaqueous phase liquid determined by this sampling approach agreed with the conceptual model for the site.     

石油污染土壤的微生物修复技术

介绍了石油污染土壤微生物修复技术的影响因素;概述了生物刺激、生物强化、固定化微生物、植物-微生物联合修复以及电动-微生物联合修复石油污染土壤的技术原理,分析了现阶段土壤修复过程中面临的难题,预测了微生物修复技术的研究方向。指出优化微生物的环境条件、培育新型高效的基因工程菌和开发经济高效的新型修复技术等将是未来微生物修复技术的发展趋势。     

Insights from years of performance that are shaping injection‐based remediation systems

Research and field experience from the past 15 years has allowed remediation professionals to purposefully design injection‐based remediation systems with a high potential for success. Industry professionals can now claim a number of achievements that were unthinkable just a few years ago: (1) we have demonstrated that maximum contaminant levels (MCLs) can be achieved for multiple contaminants; (2) we have successfully targeted dense nonaqueous‐phase liquid (DNAPL) source zones; (3) we have expanded our understanding of injection hydraulics to treat large plumes; and (4) we have collected sufficient data on rates of treatment to be more predictive regarding outcomes. The next decade will continue to evolve the design and execution of these types of systems for application to more complex problems. At this point on the timeline, questions regarding the mechanisms of treatment have largely been addressed, allowing a shift in focus to operational enhancements. Specific operational insights arising from the body of work to date that arguably will continue to shape and influence the design and execution of injection‐based remediation systems include: (1) the fact that delivery does not always equal distribution, (2) treatment optimization requires aquifer tuning, and (3) life‐cycle costs can be reduced with remedy‐optimized investigation. The number of examples that support these concepts and their ramifications to future technology refinement is already increasing, demonstrating how the refinements that can be made around these areas of focus will enhance our ability to effectively tackle larger and more complicated plumes, and do so with maximum efficiency. © 2011 Wiley Periodicals, Inc.     

Advances in photocatalytic remediation technology

The cost of remediation at hazardous waste sites is estimated at billions of dollars annually. It is imperative that more cost‐effective remediation technologies be developed, particularly to address the more complex megasites. Chlorinated hydrocarbons represent the major contaminants at many such sites. It has long been recognized that chlorinated hydrocarbons can be destroyed by photocatalytic oxidation. Traditional photocatalysts, however, have often shown inadequate destruction activity, a loss of activity over time, and poor selectivity, thereby producing substantial amounts of phosgene and chloroform by‐products. This article presents results obtained using novel photocatalyst compositions. The results demonstrate the ability to achieve high photocatalytic destruction activity for chlorinated hydrocarbons with full retention of activity over extended time periods and with complete elimination of phosgene and chloroform by‐products. © 2006 Wiley Periodicals, Inc.     

Nanotechnology for site remediation

As a remediation tool, nanotechnology holds promise for cleaning up hazardous waste sites cost‐effectively and addressing challenging site conditions, such as the presence of dense nonaqueous phase liquids (DNAPLs). Some nanoparticles, such as nanoscale zero‐valent iron (nZVI) are already in use in full‐scale projects with encouraging success. Ongoing research at the bench and pilot scale is investigating particles such as self‐assembled monolayers on mesoporous supports (SAMMS™), dendrimers, carbon nanotubes, and metalloporphyrinogens to determine how to apply their unique chemical and physical properties for full‐scale remediation. There are many unanswered questions regarding nanotechnology. Further research is needed to understand the fate and transport of free nanoparticles in the environment, whether they are persistent, and whether they have toxicological effects on biological systems. In October 2008, the U.S. Environmental Protection Agency's Office of Superfund Remediation and Technology Innovation (OSRTI) prepared a fact sheet entitled “Nanotechnology for Site Remediation,” and an accompanying list of contaminated sites where nanotechnology has been tested. The fact sheet contains information that may assist site project managers in understanding the potential applications of this group of technologies. This article provides a synopsis of the US EPA fact sheet, available at http://clu‐in.org/542F08009 , and includes background information on nanotechnology; its use in site remediation; issues related to fate, transport, and toxicity; and a discussion of performance and cost data for field tests. The site list is available at http://clu‐in.org/products/nanozvi . © 2008 Wiley Periodicals, Inc.     

1,4‐Dioxane: Emerging technologies for an emerging contaminant

The synthetic chemical, 1,4‐dioxane, is classified by the U.S. Environmental Protection Agency (EPA) as a probable human carcinogen. Between 2013 and 2015, the EPA detected 1,4‐dioxane in public drinking water supplies in 45 states at concentrations up to 33 µg/L and in groundwater from releases at hazardous waste sites across the United States. Although a Federal maximum contaminant level drinking water standard has not yet been proposed, state‐specific standards and criteria are as low as 0.3 µg/L. 1,4‐Dioxane is a recalcitrant chemical in that applications of conventional treatment technologies have had limited success in reducing concentrations in water to meet current and proposed health‐protective levels. Although mainly used as a stabilizer for the solvent 1,1,1‐trichloroethane, it has been used in other industrial processes and has been detected in a variety of consumer products, such as foods, pharmaceuticals, cosmetics, and detergents. The high aqueous solubility of 1,4‐dioxane coupled with limited solubility of chlorinated solvents typically found in conjunction with 1,4‐dioxane contamination is the primary reason for its treatment challenges. In the last several years, an alternative, cost‐effective technology has been developed that has demonstrated treatment to levels significantly lower than the Federal and state‐specific goals. This article provides a Federal and state‐by‐state summary of 1,4‐dioxane‐specific drinking water and groundwater concentration criteria and qualitative comparison of the effectiveness of conventional treatment technologies compared to the effectiveness of an alternative treatment technology. A case study is also provided to present details regarding the application of an alternative treatment technology at an active groundwater remediation site in California.     

Brownfield Sites Remediation Technology Overview,Trends, and Opportunities in China

Over decades of economic development, China's industrialization has led to significant environmental issues due to unregulated discharges into air, water, and soil. As cities continue to expand (i.e., urbanization trend) and awareness/concerns about environmental pollution rises, many industrial facilities along the edge of or within the city boundaries have been relocated or closed. This urbanization trend leaves behind idled and abandoned land that is contaminated from the former industrial activities and unregulated discharges. China released its first nationwide soil quality survey in April 2014, and the survey suggests that soil conditions in China represent a significant challenge. China has encouraged local engineering firms to demonstrate soil treatment technologies through pilot‐scale studies, but the outcomes of many demonstrations have not been promising due to the lack of remediation experience and underdeveloped technical guidelines that are needed to guide the remediation processes. During the past decade, some local soil remediation experience has been established, but it is limited for certain technologies that address their primary contaminants of concern: heavy metals and persistent organic pollutants. In 2014, national technical guidelines were published regarding environmental investigation, risk assessment, monitoring, and remediation; however, regulations and funding systems are still underdeveloped. Thus, the remediation processes that should maximize economic and environmental benefits are not streamlined. This article provides an overview of the latest regulatory developments, remediation technologies applied, technology trends, and market opportunities in China. The provided information aims to allow international remediation practitioners to better understand and appreciate this unique and emerging remediation market, which is growing fast, and to highlight the importance of developing a sustainable model that not only provides for cleanup of the environment but also supports economic development. ©2015 Wiley Periodicals, Inc.     

Comparing the Adoption of Contaminated Land Remediation Technologies in the United States,United Kingdom,and China

In many locations across the world, land contamination poses a serious threat to human health and the wider environment. For instance, a report published on April 17, 2014, revealed that China now has 16.1 percent of its land contaminated by various organic and inorganic contaminants, posing a range of challenges from human health risk to food security. The innovation and adoption of suitable remediation technologies is critical for solving land contamination issues. However, little is known about the pattern of remediation technology adoption, as well as its determining factors. This study uses a questionnaire survey in the United States, United Kingdom, and China to examine the spatial variation of remediation technology adoption. It further explores the temporal trend of remediation technology adoption using secondary data from the U.S. Superfund program. The study identified significant differences in remediation technology adoption among these countries, which are attributed to the different environmental, social, economic, and regulatory contexts. It is argued that the full implications of remediation technology adoption to sustainable development should be further studied, and policy instruments should be designed accordingly to promote those remediation technologies that align the best with long‐term sustainability. Technology developers may also use these implications to adjust their research and development priorities. © 2014 Wiley Periodicals, Inc.     

Cost Evaluation for Selected Remediation Technologies

Relatively little data are available to document the historical cost for using common remediation technologies, and site managers often must rely on information from technology vendors and predictive models, which may not accurately reflect the experiences of previous technology users. To help address these concerns, the U.S. Environmental Protection Agency (EPA) conducted an evaluation of data on historical costs of common remediation technologies. Cost curves were developed for four technologies, showing the relationship between cost for remediation and quantity of material treated. Although costs are known to be highly site‐specific and affected by many factors, the curves are useful in illustrating the variability of historical costs and the economies of scale for treating relatively large quantities of material. © 2002 Wiley Periodicals, Inc.     

Accessing EPA's hazardous waste remediation technology information

Hazardous waste remediation technologies are rapidly evolving, and it is a challenge for environmental consultants and those working in the government and public sectors to remain current with those technologies. Fortunately, the U.S. Environmental Protection Agency (EPA), through a variety of programs and initiatives, has been a leader in providing information on hazardous waste remediation technologies. This article provides an overview of EPA remediation programs and guides the reader through valuable EPA information sources including publications, databases, and on-line services.     

New paradigms for hazardous waste engineering

Today's hazardous waste engineering practice is based on the premise that the current technologies for conducting hazardous waste remediation are sufficient to solve most problems. The premise is false: Except for simple sites, the current practice cannot deliver answers with the required accuracy and precision. This article describes the huge uncertainties present in complex hazardous waste remediation efforts. It also discusses the “observational” method, which originated in the geotechnical engineering field, as a means of coping with these uncertainties during site characterization and remediation. The article includes case-study examples illustrating the use of the observational method at hazardous waste sites.     

Managing contaminated sites and the role of domestic and international forums

Domestic and international cooperation in the field of contaminated‐site management has increased dramatically in the past decade. The expected benefits of this cooperation include the reduction of duplication in remediation efforts, the coordination of contaminated‐site research, improved synergy between various stakeholders, enhanced policy development, and better information dissemination and technology transfer. This article identifies and briefly discusses key domestic and international collaborations, partnerships, and networks relating to contaminated‐site management and remediation. Also provided is information on how the forums can be accessed. Common themes identified across the forums discussed in this article include (1) the development and demonstration of innovative technologies, (2) the use of risk assessment, (3) the use of toxicology, bioavailability, and ecotoxicity testing, and (4) the increasing need to find holistic approaches for managing contaminated sites, such as guaranteed remediation programs and transfer of environment liability, and the need for understanding implications of remediation financing mechanisms. © 2001 John Wiley & Sons, Inc.